Field of the Invention
The present invention relates to a light emitting element and a method for manufacturing the light emitting element.
Description of the Related Art
Light emitting elements expected as next-generation of displays or illumination devices include an organic EL element (organic Electro-Luminescence element or organic light emitting diode). In the organic EL element, a hole injected from a hole injecting layer and electron injected from an electron injecting layer are carried to a light emitting layer respectively, then the hole and electron are recombined on an organic molecule in a light emitting part of the light emitting layer to excite the organic molecule, thereby generating light emission. Therefore, when the organic EL element is used as the display device or the illumination device, the light from the light emitting layer is required to be efficiently extracted from the surface of the organic EL element. In order to meet this demand, Japanese Patent Application Laid-open No. 2006-236748 discloses that a diffraction grating substrate is provided on a light extraction surface of the organic EL element.
In the organic EL element, moisture and oxygen may reduce luminance, luminous efficiency, and the like. In order to prevent such deterioration, the organic EL element is used in a state that the light emitting part (organic layer) is sealed with a sealing member. Methods for sealing the light emitting part include a method referred to as “surface sealing (cover sealing)” and a method referred to as “frame sealing”. The surface sealing is a method for sealing the light emitting part by covering the light emitting part with adhesive (sealing adhesive) or the like. The frame sealing is a method as described in Japanese Patent Application Laid-open No. 2012-174410. Namely, in a structure having a sealing member, such as sealing glass, which is disposed on a light emitting part on a substrate, the periphery of the sealing member is sealed with adhesive. It is said that it is possible to elongate the service life of the frame-sealed element by filling a sealed space of the structure with a desiccant or the like.